First, you must understand that "determining" or using a megohm meter is a necessary step in determining whether the compressor in the AC device is functioning properly. Megohm meter (megohm meter) is an ohmmeter used to measure the resistance of an insulator. The winding insulation of the compressor must be checked periodically to determine whether current flows through or through the insulation around the winding.

Three kinds of current

In this case, the technician measures the current while he is determining the capacitor charge current. This is a current that starts high and then drops after the insulator is charged to full voltage. Secondly, the absorption current must be determined and measured. This current is caused by moisture accumulation or contaminants present in the insulation. Oil levels, leaks through terminals and flux or contaminated refrigerants can also cause current accumulation. Third, megometers will measure conduction or leakage currents in the insulation.

The two methods

The purpose of the current measurement is to determine the quality of the compressor. The dielectric absorption rate will be determined by the technician. This is quite complex mathematics and requires specialized knowledge and skills. A 60 second grounding reading of each compressor terminal is read and megohm is measured at 30 second intervals. The terminals are grounded through a jumper between each reading. Then divide the 60-second reading by the 30-second reading. This results in a calculation called DAR. Absorption rates between 1.0 and 1.35 are a suspect range indicating system contamination. A reading between 1.4 and 1.6 is a good reading.